1. Field of the Invention
The present invention relates to a magnetic reading head using a magneto-resistive element, and more particularly, to a magnetic reading head which has an improved sensitivity by adjusting the widths of its shield layers.
2. Description of the Related Art
FIG. 1A is a schematic perspective view of a conventional magnetic reading head, and FIG. 1B is schematic conceptional view illustrating the distribution of magnetic fields in the conventional magnetic reading head.
Referring to FIG. 1A, the conventional magnetic reading head includes a magneto-resistive (MR) element 11 which is used as a sensor and shield layers 13 and 15 which enclose the MR element 11. The conventional magnetic reading head is greatly affected by a magnetic field because a width of each of the shield layers 13 and 15 is wider than a distance G between the MR element 11 and a soft underlayer 18b of a recording medium 18.
The MR element 11 used in the magnetic reading head is a sensor which uses a principle of changes in a resistance of the MR element 11 due to a relative angle difference between a magnetized direction of a free layer of the MR element 11 and a magnetized direction of a pinned layer of the MR element 11. Since the magnetized direction of the free layer of the MR element 11 varies according to a magnetized direction of the recording medium 18, the magnetic reading head can read information from the recording medium 18 by detecting the changes in resistance of the MR element 11.
The shield layers 13 and 15 serve to shield outer magnetic fields except magnetic fields formed by the magnetization of the recording medium 18 to be detected under the MR element 11 and mechanically protect the MR element 11.
However, as shown in FIG. 1B, magnetic paths are formed by the magnetization of magnetic domains opposite to lower portions of the shield layers 13 and 15 as well as by the magnetization of the recording medium 18 adjacent to the MR element 11. Thus, noise increases in proportion to areas of bottom surfaces of the lower portions of the shield layers 13 and 15, which results in the deterioration of sensitivity of the magnetic reading head when reading information.